Agricultural machines of the general character referred to in the "Abstract" hereof are well known, there being three basic types as to foldability of the wing sections; namely rear fold, vertical fold and forward fold. The forward fold appears to be the most widely favored and a good example of that type forms the subject matter of the Pratt U.S. Pat. No. 4,137,852. The machine there disclosed features three sections, each including row-crop tools (e.g. planting units), these sections being a central rear section and right and left wing sections. In operating mode, the three sections are disposed in alignement transversely to the line of draft. In folded or transport mode, the wing sections fold forwardly respectively along opposite sides of a telescopic hitch or tongue. Each section in the patent has one or more ground wheels interspaced among the planting units, which militates against extra-narrow row spacing. There are other versions of forward-fold machines which to some extent solve the narrow row problem but are fraught with other problems, especially lack of stability in transport mode and lack of convenience in converting from one mode to the other, in at least one known case requiring that the wing sections can be raised above the rear central section and thus projecting rearwardly thereof and further raising the center of gravity of the machine in transport.
According to the present invention, these problems are overcome by simple design and construction. The machine can be converted from one mode to the other and vice versa without the use of a telescopic hitch. The wheels on the wing sections are placed outwardly or forwardly so as not to intervene between row units, but are retractible rearwardly when the wings are folded so as to achieve a narrow transport width. Further, these wheels are caster wheels and can operate straight-ahead in either mode of operation and hence can serve as support wheels in either mode as well as between mode changes. The rear central section is without row units and the arrangement is such that this section is completely to the rear of the wing sections in either mode, thus more evenly distributing the weight of the machine as concerns the tractor drawbar (on which the machine tongue is supported) and also increasing the stability of the machine.
Features and advantages in addition to those set forth above will become apparent to those versed in the art as a preferred embodiment of the invention is disclosed in detail in the ensuing description and accompanying drawings.